1. Field of the Invention
This invention relates to a recessed ceiling lighting fixture and, more particularly, to a retrofit fluorescent lighting fixture having a separate housing for an electronic ballast.
2. Background Discussion
Recessed ceiling lighting is a highly desirable means of illumination, both indoors and out. Typically a cylindrical light fixture is inserted into a similarly shaped recess in the ceiling. The fixture connects with a conventional light socket or other type of electrical terminal provided in the ceiling recess for power. The fixture typically includes a trim ring around its lower periphery which covers the unsightly edges of the recess. Often, a canister-like liner is provided in the recess.
One example of such a recessed lighting fixture is disclosed in U.S. Pat. No. 4,641,228, and in several related patents. In these disclosures, a screw base is threaded into a socket within the ceiling recess for power. A flexible strap attached to the screw base extends downward through a central opening in a cover and in a reflector of a fixture. A friction ring is pushed upward along the flexible strap, drawing the reflector up into the recess until a trim-ring surrounding the reflector abuts against the ceiling.
In these patents, the light sources are high-powered, low wattage tubular fluorescent lamps powered by magnetic ballasts which control initiation and maintenance of the glow discharge ionization in the tubular lamps. The ballasts are mounted on dome-shaped reflectors proximate receptacles which receive the terminal end of the fluorescent lamps, with the tubular bodies of the lamps extending into the interior of the reflector. A hollow cover attaches over the reflector to surround the ballasts and lamp connector ends. There are certain drawbacks to the use of magnetic ballasts. First, the total harmonic distortion may be unacceptable. Secondly, the magnets are dense and add substantial relative weight to the overall fixture weight. Third, the initiation timing is delayed and the fluorescent lamps exhibit a flickering before coming fully on. Finally, the power factor for such lights are typically not sufficient to qualify for rebates often given by electric utility companies.
Additionally, in the light fixtures such as described in U.S. Pat. No. 4,641,228 and its related patents, servicing the fixture when a magnetic ballast fails is time-consuming. To service such a failure, the entire reflector must be removed and the individual ballast detached to be replaced by a new one.
There is currently a need for a more efficient, lighter and simpler to maintain fluorescent lighting fixture.